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b,x2-2x-35=0
=>(x2-2x+1)-36=0
=>(x-1)2-62=0
=>(x-1-6)(x-1+6)=0
=>(x-7)(x+5)=0
=>x=7 hoặc x=-5
a) 3/35 - (3/5 + x) = 2/7
=> 3/5 + x= 3/35- 2/7
=> 3/5 +x = -1/5
=> x = -1/5 -3/5
=> x = -4/5
b) 3/7 +1/7 : x = 3/14
=> 1/7 : x= 3/14 -3/7
=> 1/7 : x = -3/14
=> x = 1/7 : -3/14
=> x = -2/3
c) (5x-1).(2x-1/3)=0
=> \(\left[{}\begin{matrix}5x-1=0\\2x-\dfrac{1}{3}=0\end{matrix}\right.\)
=> \(\left[{}\begin{matrix}5x=0+1=1\\2x=0+\dfrac{1}{3}=\dfrac{1}{3}\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x=\dfrac{1}{5}\\x=\dfrac{1}{3}:2=\dfrac{1}{6}\end{matrix}\right.\)
Học tốt :D
a)x=-4/5
b)x=-2/3
c)\(\left\{{}\begin{matrix}5x-1=0\\2x-\dfrac{1}{3}=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}5x=1\\2x=\dfrac{1}{3}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{1}{5}\\x=\dfrac{1}{6}\end{matrix}\right.\)
Vậy.........
mik lười mong bn thông cảm
\(b,5x+2\left(x-7\right)=35\\ \Leftrightarrow5x+2x-14-35=0\\ \Leftrightarrow7x-49=0\\ \Leftrightarrow7x=49\\ \Leftrightarrow x=7\\ d,đk:x\ne2;x\ne0\\ \dfrac{x+2}{x-2}-\dfrac{1}{x}-\dfrac{2}{x^2-2x}=0\\ \Leftrightarrow\dfrac{x+2}{x-2}-\dfrac{1}{x}-\dfrac{2}{x\left(x-2\right)}=0\\ \Leftrightarrow\dfrac{x\left(x+2\right)-\left(x-2\right)-2}{x\left(x-2\right)}=0\\ \Leftrightarrow x^2+2x-x+2-2=0\\ \Leftrightarrow x^2+x=0\\ \Leftrightarrow x\left(x+1\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=0\left(kot/m\right)\\x=-1\left(t/m\right)\end{matrix}\right.\)
\(5x+2\left(x-7\right)=35\)
\(\Leftrightarrow5x+2x-14=35\)
\(\Leftrightarrow7x-14=35\)
\(\Leftrightarrow7x=49\)
\(\Leftrightarrow x=7\)
\(\text{Vậy phương trình có tập nghiệm là }S=\left\{7\right\}\)
\(\dfrac{x+2}{x-2}-\dfrac{1}{x}-\dfrac{2}{x^2-2x}=0\) \(\text{ĐKXĐ:}x\ne0;x\ne2\)
\(\Leftrightarrow\dfrac{x+2}{x-2}-\dfrac{1}{x}-\dfrac{2}{x\left(x-2\right)}=0\)
\(\Leftrightarrow\dfrac{x\left(x+2\right)}{x\left(x-2\right)}-\dfrac{x-2}{x\left(x-2\right)}-\dfrac{2}{x\left(x-2\right)}=0\)
\(\Rightarrow x^2+2x-x+2-2=0\)
\(\Leftrightarrow x^2+x=0\)
\(\Leftrightarrow x\left(x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x+1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\left(\text{loại}\right)\\x=-1\left(\text{nhận}\right)\end{matrix}\right.\)
\(\text{Vậy phương trình có tập nghiệm là }S=\left\{-1\right\}\)
\(d,x\left(x-3\right)-7x+21=0\)
\(\Leftrightarrow x\left(x-3\right)-7\left(x-3\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(x-7\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-3=0\\x-7=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=3\\x=7\end{cases}}}\)
\(a,2x\left(x-7\right)+5x-35=0\)
\(\Leftrightarrow2x\left(x-7\right)+5\left(x-7\right)=0\)
\(\Leftrightarrow\left(x-7\right)\left(2x+5\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-7=0\\2x+5=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=7\\x=-\frac{5}{2}\end{cases}}}\)
\(c,4x^2+12x+9=0\)
\(\Leftrightarrow4x^2+6x+6x+9=0\)
\(\Leftrightarrow2x\left(2x+3\right)+3\left(2x+3\right)=0\)
\(\Leftrightarrow\left(2x+3\right)\left(2x+3\right)=0\)
\(\Leftrightarrow2x+3=0\)
\(\Leftrightarrow x=-\frac{3}{2}\)
a) \(21x+7=15x+35\)
\(\Leftrightarrow21x-15x=35-7\)
\(\Leftrightarrow6x=28\)
\(\Leftrightarrow x=\frac{28}{6}\)
b)\(|5x+3|-2x=x-17\)
\(\Leftrightarrow|5x+3|=3x-17\)
\(\Leftrightarrow\orbr{\begin{cases}5x+3=3x-17\\5x+3=17-3x\end{cases}\Leftrightarrow\orbr{\begin{cases}2x=-20\\8x=14\end{cases}}}\Leftrightarrow\orbr{\begin{cases}x=-10\\x=\frac{4}{7}\end{cases}}\)
c) \(\left(5x+2\right)\left(3x-4\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}5x+2=0\\3x-4=0\end{cases}\Leftrightarrow\orbr{\begin{cases}5x=-2\\3x=4\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=-\frac{2}{5}\\x=\frac{4}{3}\end{cases}}}\)
a) \(21x+7=15x+35\)
\(\Leftrightarrow\)\(6x=28\)
\(\Leftrightarrow\)\(x=\frac{14}{3}\)
Vậy...
b) \(\left|5x+3\right|-2x=x-17\)
\(\Leftrightarrow\)\(\left|5x+3\right|=3x-17\)
Nếu \(x\ge-\frac{3}{5}\)thì pt trở thành:
\(5x+3=3x-17\)
\(\Leftrightarrow\)\(2x=-20\)
\(\Leftrightarrow\)\(x=-10\)(loại)
Nếu \(x< -\frac{3}{5}\)thì pt trở thành:
\(-5x-3=3x-17\)
\(\Leftrightarrow\)\(8x=14\)
\(\Leftrightarrow\) \(x=\frac{7}{4}\) (loại)
Vậy pt vô nghiệm
c) \(\left(5x+2\right)\left(3x-4\right)=0\)
\(\Leftrightarrow\)\(\orbr{\begin{cases}5x+2=0\\3x-4=0\end{cases}}\)
\(\Leftrightarrow\)\(\orbr{\begin{cases}x=-\frac{2}{5}\\x=\frac{4}{3}\end{cases}}\)
Vậy...
\(3x\left(25x+15\right)-35\left(5x+3\right)=0\\ \Leftrightarrow75x^2+45x-175x-105=0\\\Leftrightarrow 75x^2-130x-105=0\\\Leftrightarrow 75\left(x^2-\frac{26}{15}x-\frac{7}{5}\right)=0\\\Leftrightarrow x^2-\frac{26}{15}x-\frac{7}{5}=0\\\Leftrightarrow x^2+\frac{3}{5}x-\frac{7}{3}x-\frac{7}{5}=0\\\Leftrightarrow \left(x+\frac{3}{5}\right)\left(x-\frac{7}{3}\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x+\frac{3}{5}=0\\x-\frac{7}{3}=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-\frac{3}{5}\\x=\frac{7}{3}\end{matrix}\right.\)
Vậy tập nghiệm của phương trình trên là \(S=\left\{-\frac{3}{5};\frac{7}{3}\right\}\)
\(1.\left(5x+1\right)^2=\left(3x-2\right)^2\\ \Leftrightarrow\left(5x+1\right)^2-\left(3x-2\right)^2=0\\ \Leftrightarrow\left(5x+1-3x+2\right)\left(5x+1+3x-2\right)=0\\\Leftrightarrow \left(2x+3\right)\left(8x-1\right)=0\\\Leftrightarrow \left[{}\begin{matrix}2x+3=0\\8x-1=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-\frac{2}{3}\\x=\frac{1}{8}\end{matrix}\right.\)
Vậy tập nghiệm của phương trình trên là \(S=\left\{-\frac{2}{3};\frac{1}{8}\right\}\)
a) 5x +3=2x-8 <=>5x-2x=-8-3 <=>3x=-11 <=> x=\(\dfrac{-11}{3}\)
b)6x-3(x+2)=5x+3<=> (6-3-5)x-9=0 <=> x=\(\dfrac{-9}{2}\)
c) (3x-9)(5x+10)=0<=> \(\left[{}\begin{matrix}3x-9=0\\5x+10=0\end{matrix}\right.\) <=> \(\left[{}\begin{matrix}x=3\\x=-2\end{matrix}\right.\)
d)8x(x+2)+16(x+2)=0<=>(x+2)(8x+16)=0<=>\(\left[{}\begin{matrix}x=-2\\x=-2\end{matrix}\right.\)
e)x2 -12x+35=0 <=>\(\left[{}\begin{matrix}x=7\\x=5\end{matrix}\right.\)
Bài làm :
\(a,\left(7x-7\right)\left(x-3\right)=0\)
\(\Rightarrow\orbr{\begin{cases}7x-7=0\\x-3=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=1\\x=3\end{cases}}\)
Vậy x = 1 hoặc x = 3 .
\(b,108-18x=54\)
\(18x=108-54\)
\(18x=54\)
\(x=54:18\)
\(x=3\)
\(c,35.\left(x-10\right)=35\)
\(x-10=35:35\)
\(x-10=1\)
\(x=1+10\)
\(x=11\)
\(d,3x+5x=40\)
\(\left(3+5\right)x=40\)
\(8x=40\)
\(x=40:8\)
\(x=5\)
Học tốt
a. ( 7x - 7 ) ( x - 3 ) = 0
<=>\(\orbr{\begin{cases}7x-7=0\\x-3=0\end{cases}}\)<=>\(\orbr{\begin{cases}x=1\\x=3\end{cases}}\)
b. 108 - 18x = 54
=> 18x = 54
=> x = 3
c. 35 ( x - 10 ) = 35
=> x - 10 = 1
=> x = 11
d. 3x + 5x = 40
=> 8x = 40
=> x = 5
\(\left(x+7\right)^2-5x-35=0\)
\(\Rightarrow\left(x+7\right)^2-5.\left(x+7\right)=0\)
\(\Rightarrow\left(x+7\right).\left(x+7-5\right)=0\)
\(\Rightarrow\left(x+7\right).\left(x+2\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x+7=0\\x+2=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=-7\\x=-2\end{cases}}\)